  (function($){
            $.fn.placeholder = function(options){
                var opts = $.extend({}, $.fn.placeholder.defaults, options);
                var isIE = document.all ? true : false;
                return this.each(function(){
                    var _this = this,
                        placeholderValue =_this.getAttribute("placeholder"); //缓存默认的placeholder值
                    if(isIE){
                        _this.setAttribute("value",placeholderValue);
                        _this.onfocus = function(){
                            $.trim(_this.value) == placeholderValue ? _this.value = "" : '';
                        };
                        _this.onblur = function(){
                            $.trim(_this.value) == "" ? _this.value = placeholderValue : '';
                        };
                    }
                });
            };
        })(jQuery);
      
